“Should you warn readers about not updating every driver in Windows — or at least those in Vista? Some driver updates require reactivation of Vista. I don’t know specifically which drivers trigger reactivation (I updated several at once), but maybe Fred could shed some light on the subject.”

Product activation first appeared in XP and has been tweaked several times since then. WPA is nominally an anti-piracy tool that’s supposed to detect whether a copy of Windows is being installed illegally on multiple systems.

In essence, Windows makes a system inventory when it’s first installed and then checks to see whether the OS is being placed on the same core hardware each time its installation routine wakes up. If Windows thinks it’s being installed on a different system, it asks to be reactivated.

WPA accommodates normal hardware upgrades from time to time so that you can add more RAM and can implement other system enhancements without requiring reactivation. However, a major hardware change (such as installing a new motherboard) or even many small hardware changes can trigger the reactivation flag.

Some routine operations can also prompt a reactivation. For example, a system’s WPA records are stored on the hard drive, so reformatting the drive or otherwise losing or corrupting the activation records will generate a request for reactivation.

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